Browsing by Subject "LC-MS"

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  • Jääskeläinen, Tiina; Kärkkäinen, Olli; Jokkala, Jenna; Klåvus, Anton; Heinonen, Seppo; Auriola, Seppo; Lehtonen, Marko; FINNPEC Core Invest Grp; Hanhineva, Kati; Laivuori, Hannele (2021)
    IntroductionMaternal metabolism changes substantially during pregnancy. However, few studies have used metabolomics technologies to characterize changes across gestation.Objectives and methodsWe applied liquid chromatography-mass spectrometry (LC-MS) based non-targeted metabolomics to determine whether the metabolic profile of serum differs throughout the pregnancy between pre-eclamptic and healthy women in the FINNPEC (Finnish Genetics of Preeclampsia Consortium) Study. Serum samples were available from early and late pregnancy.ResultsProgression of pregnancy had large-scale effects to the serum metabolite profile. Altogether 50 identified metabolites increased and 49 metabolites decreased when samples of early pregnancy were compared to samples of late pregnancy. The metabolic signatures of pregnancy were largely shared in pre-eclamptic and healthy women, only urea, monoacylglyceride 18:1 and glycerophosphocholine were identified to be increased in the pre-eclamptic women when compared to healthy controls.ConclusionsOur study highlights the need of large-scale longitudinal metabolomic studies in non-complicated pregnancies before more detailed understanding of metabolism in adverse outcomes could be provided. Our findings are one of the first steps for a broader metabolic understanding of the physiological changes caused by pregnancy per se.
  • Koivula, Teija; Laine, Jaana; Lipponen, Tiina; Perhola, Outi; Kämäräinen, Eeva-Liisa; Bergström, Kim; Solin, Olof (AKADEMIAI KIADO RT., 2010)
  • Mechchate, Hamza; Es-safi, Imane; Conte, Raffaele; Hano, Christophe; Amaghnouje, Amal; Jawhari, Fatima Zahra; Radouane, Nabil; Bencheikh, Noureddine; Grafov, Andriy; Bousta, Dalila (2021)
    Flaxseed is an oilseed (45-50% oil on a dry-weight basis) crop. Its oil has demonstrated multiple health benefits and industrial applications. The goal of this research was to evaluate the antidiabetic and anti-inflammatory potential of the free polyphenol fraction of flax (Linum usitatissimum L.) seeds (PLU), based on their use in traditional medicine. Mice with alloxan-induced diabetes were used to study the antidiabetic activity of PLU in vivo, with an oral administration of 25 and 50 mg/kg over 28 days. Measurements of body weight and fasting blood glucose (FBG) were carried out weekly, and biochemical parameters were evaluated. An oral glucose tolerance test was also performed. Inhibitory activities of PLU on alpha-amylase and alpha-glucosidase activities were evaluated in vitro. The anti-inflammatory was evaluated in vivo in Wistar rats using the paw edema induction Test by carrageenan, and in vitro using the hemolysis ratio test. PLU administration to diabetic mice during the study period improved their body weight and FBG levels remarkably. In vitro inhibitory activity of digestive enzymes indicated that they may be involved in the proposed mode of action of PLU extract. Qualitative results of PLU revealed the presence of 18 polyphenols. These findings support daily consumption of flaxseed for people with diabetes, and suggest that polyphenols in flaxseed may serve as dietary supplements or novel phytomedicines to treat diabetes and its complications.
  • Kangas, Heli (University of Helsinki, 2010)
    This thesis describes current and past n-in-one methods and presents three early experimental studies using mass spectrometry and the triple quadrupole instrument on the application of n-in-one in drug discovery. N-in-one strategy pools and mix samples in drug discovery prior to measurement or analysis. This allows the most promising compounds to be rapidly identified and then analysed. Nowadays properties of drugs are characterised earlier and in parallel with pharmacological efficacy. Studies presented here use in vitro methods as caco-2 cells and immobilized artificial membrane chromatography for drug absorption and lipophilicity measurements. The high sensitivity and selectivity of liquid chromatography mass spectrometry are especially important for new analytical methods using n-in-one. In the first study, the fragmentation patterns of ten nitrophenoxy benzoate compounds, serial homology, were characterised and the presence of the compounds was determined in a combinatorial library. The influence of one or two nitro substituents and the alkyl chain length of methyl to pentyl on collision-induced fragmentation was studied, and interesting structurefragmentation relationships were detected. Two nitro group compounds increased fragmentation compared to one nitro group, whereas less fragmentation was noted in molecules with a longer alkyl chain. The most abundant product ions were nitrophenoxy ions, which were also tested in the precursor ion screening of the combinatorial library. In the second study, the immobilized artificial membrane chromatographic method was transferred from ultraviolet detection to mass spectrometric analysis and a new method was developed. Mass spectra were scanned and the chromatographic retention of compounds was analysed using extract ion chromatograms. When changing detectors and buffers and including n-in-one in the method, the results showed good correlation. Finally, the results demonstrated that mass spectrometric detection with gradient elution can provide a rapid and convenient n-in-one method for ranking the lipophilic properties of several structurally diverse compounds simultaneously. In the final study, a new method was developed for caco-2 samples. Compounds were separated by liquid chromatography and quantified by selected reaction monitoring using mass spectrometry. This method was used for caco-2 samples, where absorption of ten chemically and physiologically different compounds was screened using both single and nin- one approaches. These three studies used mass spectrometry for compound identification, method transfer and quantitation in the area of mixture analysis. Different mass spectrometric scanning modes for the triple quadrupole instrument were used in each method. Early drug discovery with n-in-one is area where mass spectrometric analysis, its possibilities and proper use, is especially important.
  • Han, Li (Helsingin yliopisto, 2015)
    Trichothecenes, as a dominant group of Fusarium mycotoxins, have received lots of scientific attention due to their wide contamination of human food and animal feed. Besides native trichothecenes, their conjugated forms the so-called masked mycotoxins, have also been somewhat studied in recent years due to their potential harmful impact. Beer, as one cereal-derived beverage, encounters the threat of trichothecene contamination. During beer fermentation, trichothecenes may be biotransformed into metabolites, which could potentially exert toxicological implications on beer consumers. The aim of this study was to investigate the metabolic fate of several major trichothecenes, including T-2 toxin (T-2), HT-2 toxin (HT-2), deoxynivalenol (DON) and its masked form deoxynivalenol-3-glucoside (D3G) during beer fermentation by lager yeast. A four-day fermentation experiment was conducted with four analytes inoculated in 11.5°Plato wort at the initial stage of fermentation individually or as a mixture with various concentrations. A reliable and efficient method was developed for the kinetic study of trichothecenes by liquid chromatography-triple quadrupole-mass spectrometry (LC-TQ-MS). After four-day fermentation, an approximate 10-40% decrease of all analytes was observed. The missing trichothecenes were very likely bound with yeast cell wall or biotransformed to their masked forms metabolic reactions. Further identification of the masked metabolites was fulfilled by analysing concentrated samples with liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-Q-Tof-MS). Several putative masked metabolites were annotated, including D3G and acetyl-DON in DON-dosed samples, acetyl-T-2 and HT-2 in T-2-dosed samples and T-2/3-acetyl-HT-2 in HT-2 samples. The stability of D3G during fermentation was for the first time investigated and was found stable under brewing fermentation conditions.
  • Heininen, Juho; Julku, Ulrika; Myöhänen, Timo; Kotiaho, Tapio; Kostiainen, Risto (2021)
    We developed a new multiplexed reversed phase liquid chromatography-high resolution tandem mass spectrometric (LC-MS/MS) method. The method is based on isobaric labeling with a tandem mass tag (TMT10-plex) and stable isotope-labeled internal standards, and was used to analyze amino acids in mouse brain microdialysis samples. The TMT10-plex labeling of amino acids allowed analysis of ten samples in one LC-MS/MS run, significantly increasing the sample throughput. The method provides good chromatographic performance (peak half-width between 0.04-0.12 min), allowing separation of all TMTlabeled amino acids with acceptable resolution and high sensitivity (limits of detection typically around 10 nM). The use of stable isotope-labeled internal standards, together with TMT10-plex labeling, ensured good repeatability (relative standard deviation 0.994), indicating good quantitative performance of the multiplexed method. The method was applied to study the effect of d-amphetamine microdialysis perfusion on amino acid concentrations in the mouse brain. All amino acids were reliably detected and quantified, indicating that the method is sensitive enough to detect low concentrations of amino acids in brain microdialysis samples. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
  • Zeng, Xin (Helsingfors universitet, 2014)
    The literature review part describes a whey protein, ?-lactalbumin (ALA) and its oxidation, aronia (Aronia melanocarpa) procyanidins including their chemistry and analysis, as well as interactions between protein and plant phenolics. The aim of the thesis was to study the oxidation of tryptic peptides of ALA with and without procyanidins. Fractions containing both procyanidin dimers and trimers were collected from aronia juice proanthocyanidins with preparative-HPLC thereafter identified and quantified with UHPLC and NP-HPLC. ALA was digested by modified trypsin and the subsequent peptides were fractionated with preparative-HPLC. The selected peptides were WLAHKALC (m/z 936) and LDQWLCEK (m/z 1034), containing specific amino acids prone to oxidation. The oxidation of peptides with and without procyanidins was catalysed by ascorbic acid, H2O2 and FeCl3, and lasted for 14 days. Oxidation was monitored with LC-MS using samples collected on days 0, 1, 7 and 14. For peptide-phenolic interaction studies, peptide WLAHKALC (m/z 936) was incubated with procyanidin B2 standard (dimer) and peptide LDQWLCEK (m/z 1034) with aronia procyanidin dimers and trimers with a 10:1 ratio. Dimeric and trimeric procyanidins exhibited antioxidant activity towards selected peptides. Possible interaction products were not detected. For further investigations of interaction, higher concentration and ratio of peptides and procyanidins as well as expanding the MS detection range are recommended. Intensive research of oxidation products of ALA peptides is needed to accomplish a thorough understanding of the oxidation and other interaction reactions of ALA peptides with other food constituents.
  • Lindström, Mikael; Valkonen, Miia; Tohmola, Niina; Renkonen, Risto; Strandin, Tomas; Vaheri, Antti; Itkonen, Outi (2019)
    Background: Bradykinin is an important mediator of inflammation and vascular permeability and could have an important role in the development of septic shock. Measurement of bradykinin by immunological methods may suffer from interference and lack of specificity. We developed and validated a liquid chromatography mass spectrometry assay (LC-MS/MS) for plasma bradykinin. Methods: We used plasma samples from healthy volunteers (n = 19) and patients with septic shock (n = 47). Stable isotope bradykinin internal standard was added to samples before solid-phase extraction and quantification by LC-MS/MS. Stability of bradykinin was studied for 12 months. Results: Our assay has good sensitivity (0.1 nmol/l) and a wide linear range (0.1-1000 nmol/1). Bradykinin added to plasma was stable for 12 months at -20 degrees C when a mixture of protease inhibitors was added at sampling but degraded during repeated freezing and thawing. Bradykinin concentration in plasma from septic shock patients (<0.1-0.6 nmol/l) did not change significantly during shock and recovery but differed slightly from that in healthy individuals (0.5-1.1 nmol/1). Conclusions: Our bradykinin assay was successfully used to determine bradykinin concentrations in plasma samples. Intensive care unit patients with septic shock had low concentrations of plasma bradykinin during both shock and recovery phases.
  • Nandania, Jatin; Peddinti, Gopal; Pessia, Alberto; Kokkonen, Meri; Velagapudi, Vidya (2018)
    The use of metabolomics profiling to understand the metabolism under different physiological states has increased in recent years, which created the need for robust analytical platforms. Here, we present a validated method for targeted and semiquantitative analysis of 102 polar metabolites that cover major metabolic pathways from 24 classes in a single 17.5-min assay. The method has been optimized for a wide range of biological matrices from various organisms, and involves automated sample preparation and data processing using an inhouse developed R-package. To ensure reliability, the method was validated for accuracy, precision, selectivity, specificity, linearity, recovery, and stability according to European Medicines Agency guidelines. We demonstrated an excellent repeatability of retention times (CV <4%), calibration curves (R-2 > 0.980) in their respective wide dynamic concentration ranges (CV <3%), and concentrations (CV <25%) of quality control samples interspersed within 25 batches analyzed over a period of one year. The robustness was demonstrated through a high correlation between metabolite concentrations measured using our method and the NIST reference values (R-2 = 0.967), including cross-platform comparability against the BIOCRATES AbsoluteIDQp180 kit (R-2 = 0.975) and NMR analyses (R-2 = 0.884). We have shown that our method can be successfully applied in many biomedical research fields and clinical trials, including epidemiological studies for biomarker discovery. In summary, a thorough validation demonstrated that our method is reproducible, robust, reliable, and suitable for metabolomics studies.